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comparison: improve "foo = min(...);" assignment handling
[smatch.git] / smatch_comparison.c
blob2f33c8fd8454dbdf2279d639d001a2b8c899497f
1 /*
2 * Copyright (C) 2012 Oracle.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
16 */
17
18 /*
19 * The point here is to store the relationships between two variables.
20 * Ie: y > x.
21 * To do that we create a state with the two variables in alphabetical order:
22 * ->name = "x vs y" and the state would be "<". On the false path the state
23 * would be ">=".
24 *
25 * Part of the trick of it is that if x or y is modified then we need to reset
26 * the state. We need to keep a list of all the states which depend on x and
27 * all the states which depend on y. The link_id code handles this.
28 *
29 */
30
31 #include "smatch.h"
32 #include "smatch_extra.h"
33 #include "smatch_slist.h"
34
35 static int compare_id;
36 static int link_id;
37 static int inc_dec_id;
38 static int inc_dec_link_id;
39
40 static void add_comparison(struct expression *left, int comparison, struct expression *right);
41
42 /* for handling for loops */
43 STATE(start);
44 STATE(incremented);
45
46 ALLOCATOR(compare_data, "compare data");
47
48 static struct symbol *vsl_to_sym(struct var_sym_list *vsl)
49 {
50 struct var_sym *vs;
51
52 if (!vsl)
53 return NULL;
54 if (ptr_list_size((struct ptr_list *)vsl) != 1)
55 return NULL;
56 vs = first_ptr_list((struct ptr_list *)vsl);
57 return vs->sym;
58 }
59
60 struct smatch_state *alloc_compare_state(
61 struct expression *left,
62 const char *left_var, struct var_sym_list *left_vsl,
63 int comparison,
64 struct expression *right,
65 const char *right_var, struct var_sym_list *right_vsl)
66 {
67 struct smatch_state *state;
68 struct compare_data *data;
69
70 state = __alloc_smatch_state(0);
71 state->name = alloc_sname(show_special(comparison));
72 data = __alloc_compare_data(0);
73 data->left = left;
74 data->left_var = alloc_sname(left_var);
75 data->left_vsl = clone_var_sym_list(left_vsl);
76 data->comparison = comparison;
77 data->right = right;
78 data->right_var = alloc_sname(right_var);
79 data->right_vsl = clone_var_sym_list(right_vsl);
80 state->data = data;
81 return state;
82 }
83
84 int state_to_comparison(struct smatch_state *state)
85 {
86 if (!state || !state->data)
87 return 0;
88 return ((struct compare_data *)state->data)->comparison;
89 }
90
91 /*
92 * flip_comparison() reverses the op left and right. So "x >= y" becomes "y <= x".
93 */
94 int flip_comparison(int op)
95 {
96 switch (op) {
97 case 0:
98 return 0;
99 case '<':
100 return '>';
101 case SPECIAL_UNSIGNED_LT:
102 return SPECIAL_UNSIGNED_GT;
103 case SPECIAL_LTE:
104 return SPECIAL_GTE;
105 case SPECIAL_UNSIGNED_LTE:
106 return SPECIAL_UNSIGNED_GTE;
107 case SPECIAL_EQUAL:
108 return SPECIAL_EQUAL;
109 case SPECIAL_NOTEQUAL:
110 return SPECIAL_NOTEQUAL;
111 case SPECIAL_GTE:
112 return SPECIAL_LTE;
113 case SPECIAL_UNSIGNED_GTE:
114 return SPECIAL_UNSIGNED_LTE;
115 case '>':
116 return '<';
117 case SPECIAL_UNSIGNED_GT:
118 return SPECIAL_UNSIGNED_LT;
119 default:
120 sm_msg("internal smatch bug. unhandled comparison %d", op);
121 return op;
122 }
123 }
124
125 int negate_comparison(int op)
126 {
127 switch (op) {
128 case 0:
129 return 0;
130 case '<':
131 return SPECIAL_GTE;
132 case SPECIAL_UNSIGNED_LT:
133 return SPECIAL_UNSIGNED_GTE;
134 case SPECIAL_LTE:
135 return '>';
136 case SPECIAL_UNSIGNED_LTE:
137 return SPECIAL_UNSIGNED_GT;
138 case SPECIAL_EQUAL:
139 return SPECIAL_NOTEQUAL;
140 case SPECIAL_NOTEQUAL:
141 return SPECIAL_EQUAL;
142 case SPECIAL_GTE:
143 return '<';
144 case SPECIAL_UNSIGNED_GTE:
145 return SPECIAL_UNSIGNED_LT;
146 case '>':
147 return SPECIAL_LTE;
148 case SPECIAL_UNSIGNED_GT:
149 return SPECIAL_UNSIGNED_LTE;
150 default:
151 sm_msg("internal smatch bug. unhandled comparison %d", op);
152 return op;
153 }
154 }
155
156 static int rl_comparison(struct range_list *left_rl, struct range_list *right_rl)
157 {
158 sval_t left_min, left_max, right_min, right_max;
159 struct symbol *type = &int_ctype;
160
161 if (!left_rl || !right_rl)
162 return 0;
163
164 if (type_positive_bits(rl_type(left_rl)) > type_positive_bits(type))
165 type = rl_type(left_rl);
166 if (type_positive_bits(rl_type(right_rl)) > type_positive_bits(type))
167 type = rl_type(right_rl);
168
169 left_rl = cast_rl(type, left_rl);
170 right_rl = cast_rl(type, right_rl);
171
172 left_min = rl_min(left_rl);
173 left_max = rl_max(left_rl);
174 right_min = rl_min(right_rl);
175 right_max = rl_max(right_rl);
176
177 if (left_min.value == left_max.value &&
178 right_min.value == right_max.value &&
179 left_min.value == right_min.value)
180 return SPECIAL_EQUAL;
181
182 if (sval_cmp(left_max, right_min) < 0)
183 return '<';
184 if (sval_cmp(left_max, right_min) == 0)
185 return SPECIAL_LTE;
186 if (sval_cmp(left_min, right_max) > 0)
187 return '>';
188 if (sval_cmp(left_min, right_max) == 0)
189 return SPECIAL_GTE;
190
191 return 0;
192 }
193
194 static int comparison_from_extra(struct expression *a, struct expression *b)
195 {
196 struct range_list *left, *right;
197
198 if (!get_implied_rl(a, &left))
199 return 0;
200 if (!get_implied_rl(b, &right))
201 return 0;
202
203 return rl_comparison(left, right);
204 }
205
206 static struct range_list *get_orig_rl(struct var_sym_list *vsl)
207 {
208 struct symbol *sym;
209 struct smatch_state *state;
210
211 if (!vsl)
212 return NULL;
213 sym = vsl_to_sym(vsl);
214 if (!sym || !sym->ident)
215 return NULL;
216 state = get_orig_estate(sym->ident->name, sym);
217 return estate_rl(state);
218 }
219
220 static struct smatch_state *unmatched_comparison(struct sm_state *sm)
221 {
222 struct compare_data *data = sm->state->data;
223 struct range_list *left_rl, *right_rl;
224 int op;
225
226 if (!data)
227 return &undefined;
228
229 if (strstr(data->left_var, " orig"))
230 left_rl = get_orig_rl(data->left_vsl);
231 else if (!get_implied_rl_var_sym(data->left_var, vsl_to_sym(data->left_vsl), &left_rl))
232 return &undefined;
233
234 if (strstr(data->right_var, " orig"))
235 right_rl = get_orig_rl(data->right_vsl);
236 else if (!get_implied_rl_var_sym(data->right_var, vsl_to_sym(data->right_vsl), &right_rl))
237 return &undefined;
238
239 op = rl_comparison(left_rl, right_rl);
240 if (op)
241 return alloc_compare_state(
242 data->left, data->left_var, data->left_vsl,
243 op,
244 data->right, data->right_var, data->right_vsl);
245
246 return &undefined;
247 }
248
249 /* remove_unsigned_from_comparison() is obviously a hack. */
250 int remove_unsigned_from_comparison(int op)
251 {
252 switch (op) {
253 case SPECIAL_UNSIGNED_LT:
254 return '<';
255 case SPECIAL_UNSIGNED_LTE:
256 return SPECIAL_LTE;
257 case SPECIAL_UNSIGNED_GTE:
258 return SPECIAL_GTE;
259 case SPECIAL_UNSIGNED_GT:
260 return '>';
261 default:
262 return op;
263 }
264 }
265
266 /*
267 * This is for when you merge states "a < b" and "a == b", the result is that
268 * we can say for sure, "a <= b" after the merge.
269 */
270 int merge_comparisons(int one, int two)
271 {
272 int LT, EQ, GT;
273
274 if (!one || !two)
275 return 0;
276
277 one = remove_unsigned_from_comparison(one);
278 two = remove_unsigned_from_comparison(two);
279
280 if (one == two)
281 return one;
282
283 LT = EQ = GT = 0;
284
285 switch (one) {
286 case '<':
287 LT = 1;
288 break;
289 case SPECIAL_LTE:
290 LT = 1;
291 EQ = 1;
292 break;
293 case SPECIAL_EQUAL:
294 EQ = 1;
295 break;
296 case SPECIAL_GTE:
297 GT = 1;
298 EQ = 1;
299 break;
300 case '>':
301 GT = 1;
302 }
303
304 switch (two) {
305 case '<':
306 LT = 1;
307 break;
308 case SPECIAL_LTE:
309 LT = 1;
310 EQ = 1;
311 break;
312 case SPECIAL_EQUAL:
313 EQ = 1;
314 break;
315 case SPECIAL_GTE:
316 GT = 1;
317 EQ = 1;
318 break;
319 case '>':
320 GT = 1;
321 }
322
323 if (LT && EQ && GT)
324 return 0;
325 if (LT && EQ)
326 return SPECIAL_LTE;
327 if (LT && GT)
328 return SPECIAL_NOTEQUAL;
329 if (LT)
330 return '<';
331 if (EQ && GT)
332 return SPECIAL_GTE;
333 if (GT)
334 return '>';
335 return 0;
336 }
337
338 /*
339 * This is for if you have "a < b" and "b <= c". Or in other words,
340 * "a < b <= c". You would call this like get_combined_comparison('<', '<=').
341 * The return comparison would be '<'.
342 *
343 * This function is different from merge_comparisons(), for example:
344 * merge_comparison('<', '==') returns '<='
345 * get_combined_comparison('<', '==') returns '<'
346 */
347 int combine_comparisons(int left_compare, int right_compare)
348 {
349 int LT, EQ, GT;
350
351 left_compare = remove_unsigned_from_comparison(left_compare);
352 right_compare = remove_unsigned_from_comparison(right_compare);
353
354 LT = EQ = GT = 0;
355
356 switch (left_compare) {
357 case '<':
358 LT++;
359 break;
360 case SPECIAL_LTE:
361 LT++;
362 EQ++;
363 break;
364 case SPECIAL_EQUAL:
365 return right_compare;
366 case SPECIAL_GTE:
367 GT++;
368 EQ++;
369 break;
370 case '>':
371 GT++;
372 }
373
374 switch (right_compare) {
375 case '<':
376 LT++;
377 break;
378 case SPECIAL_LTE:
379 LT++;
380 EQ++;
381 break;
382 case SPECIAL_EQUAL:
383 return left_compare;
384 case SPECIAL_GTE:
385 GT++;
386 EQ++;
387 break;
388 case '>':
389 GT++;
390 }
391
392 if (LT == 2) {
393 if (EQ == 2)
394 return SPECIAL_LTE;
395 return '<';
396 }
397
398 if (GT == 2) {
399 if (EQ == 2)
400 return SPECIAL_GTE;
401 return '>';
402 }
403 return 0;
404 }
405
406 int filter_comparison(int orig, int op)
407 {
408 if (orig == op)
409 return orig;
410
411 orig = remove_unsigned_from_comparison(orig);
412 op = remove_unsigned_from_comparison(op);
413
414 switch (orig) {
415 case 0:
416 return op;
417 case '<':
418 switch (op) {
419 case '<':
420 case SPECIAL_LTE:
421 case SPECIAL_NOTEQUAL:
422 return '<';
423 }
424 return 0;
425 case SPECIAL_LTE:
426 switch (op) {
427 case '<':
428 case SPECIAL_LTE:
429 case SPECIAL_EQUAL:
430 return op;
431 case SPECIAL_NOTEQUAL:
432 return '<';
433 }
434 return 0;
435 case SPECIAL_EQUAL:
436 switch (op) {
437 case SPECIAL_LTE:
438 case SPECIAL_EQUAL:
439 case SPECIAL_GTE:
440 case SPECIAL_UNSIGNED_LTE:
441 case SPECIAL_UNSIGNED_GTE:
442 return SPECIAL_EQUAL;
443 }
444 return 0;
445 case SPECIAL_NOTEQUAL:
446 switch (op) {
447 case '<':
448 case SPECIAL_LTE:
449 return '<';
450 case SPECIAL_UNSIGNED_LT:
451 case SPECIAL_UNSIGNED_LTE:
452 return SPECIAL_UNSIGNED_LT;
453 case SPECIAL_NOTEQUAL:
454 return op;
455 case '>':
456 case SPECIAL_GTE:
457 return '>';
458 case SPECIAL_UNSIGNED_GT:
459 case SPECIAL_UNSIGNED_GTE:
460 return SPECIAL_UNSIGNED_GT;
461 }
462 return 0;
463 case SPECIAL_GTE:
464 switch (op) {
465 case SPECIAL_LTE:
466 return SPECIAL_EQUAL;
467 case '>':
468 case SPECIAL_GTE:
469 case SPECIAL_EQUAL:
470 return op;
471 case SPECIAL_NOTEQUAL:
472 return '>';
473 }
474 return 0;
475 case '>':
476 switch (op) {
477 case '>':
478 case SPECIAL_GTE:
479 case SPECIAL_NOTEQUAL:
480 return '>';
481 }
482 return 0;
483 case SPECIAL_UNSIGNED_LT:
484 switch (op) {
485 case SPECIAL_UNSIGNED_LT:
486 case SPECIAL_UNSIGNED_LTE:
487 case SPECIAL_NOTEQUAL:
488 return SPECIAL_UNSIGNED_LT;
489 }
490 return 0;
491 case SPECIAL_UNSIGNED_LTE:
492 switch (op) {
493 case SPECIAL_UNSIGNED_LT:
494 case SPECIAL_UNSIGNED_LTE:
495 case SPECIAL_EQUAL:
496 return op;
497 case SPECIAL_NOTEQUAL:
498 return SPECIAL_UNSIGNED_LT;
499 case SPECIAL_UNSIGNED_GTE:
500 return SPECIAL_EQUAL;
501 }
502 return 0;
503 case SPECIAL_UNSIGNED_GTE:
504 switch (op) {
505 case SPECIAL_UNSIGNED_LTE:
506 return SPECIAL_EQUAL;
507 case SPECIAL_NOTEQUAL:
508 return SPECIAL_UNSIGNED_GT;
509 case SPECIAL_EQUAL:
510 case SPECIAL_UNSIGNED_GTE:
511 case SPECIAL_UNSIGNED_GT:
512 return op;
513 }
514 return 0;
515 case SPECIAL_UNSIGNED_GT:
516 switch (op) {
517 case SPECIAL_UNSIGNED_GT:
518 case SPECIAL_UNSIGNED_GTE:
519 case SPECIAL_NOTEQUAL:
520 return SPECIAL_UNSIGNED_GT;
521 }
522 return 0;
523 }
524 return 0;
525 }
526
527 static void pre_merge_hook(struct sm_state *sm)
528 {
529 struct compare_data *data = sm->state->data;
530 int other;
531
532 if (!data)
533 return;
534 other = get_comparison(data->left, data->right);
535 if (!other)
536 return;
537
538 set_state(compare_id, sm->name, NULL,
539 alloc_compare_state(data->left, data->left_var, data->left_vsl,
540 other,
541 data->right, data->right_var, data->right_vsl));
542 }
543
544 struct smatch_state *merge_compare_states(struct smatch_state *s1, struct smatch_state *s2)
545 {
546 struct compare_data *data = s1->data;
547 int op;
548
549 op = merge_comparisons(state_to_comparison(s1), state_to_comparison(s2));
550 if (op)
551 return alloc_compare_state(
552 data->left, data->left_var, data->left_vsl,
553 op,
554 data->right, data->right_var, data->right_vsl);
555 return &undefined;
556 }
557
558 static struct smatch_state *alloc_link_state(struct string_list *links)
559 {
560 struct smatch_state *state;
561 static char buf[256];
562 char *tmp;
563 int i;
564
565 state = __alloc_smatch_state(0);
566
567 i = 0;
568 FOR_EACH_PTR(links, tmp) {
569 if (!i++) {
570 snprintf(buf, sizeof(buf), "%s", tmp);
571 } else {
572 append(buf, ", ", sizeof(buf));
573 append(buf, tmp, sizeof(buf));
574 }
575 } END_FOR_EACH_PTR(tmp);
576
577 state->name = alloc_sname(buf);
578 state->data = links;
579 return state;
580 }
581
582 static void save_start_states(struct statement *stmt)
583 {
584 struct symbol *param;
585 char orig[64];
586 char state_name[128];
587 struct smatch_state *state;
588 struct string_list *links;
589 char *link;
590
591 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
592 struct var_sym_list *left_vsl = NULL;
593 struct var_sym_list *right_vsl = NULL;
594
595 if (!param->ident)
596 continue;
597 snprintf(orig, sizeof(orig), "%s orig", param->ident->name);
598 snprintf(state_name, sizeof(state_name), "%s vs %s", param->ident->name, orig);
599 add_var_sym(&left_vsl, param->ident->name, param);
600 add_var_sym(&right_vsl, orig, param);
601 state = alloc_compare_state(
602 NULL, param->ident->name, left_vsl,
603 SPECIAL_EQUAL,
604 NULL, alloc_sname(orig), right_vsl);
605 set_state(compare_id, state_name, NULL, state);
606
607 link = alloc_sname(state_name);
608 links = NULL;
609 insert_string(&links, link);
610 state = alloc_link_state(links);
611 set_state(link_id, param->ident->name, param, state);
612 } END_FOR_EACH_PTR(param);
613 }
614
615 static struct smatch_state *merge_links(struct smatch_state *s1, struct smatch_state *s2)
616 {
617 struct smatch_state *ret;
618 struct string_list *links;
619
620 links = combine_string_lists(s1->data, s2->data);
621 ret = alloc_link_state(links);
622 return ret;
623 }
624
625 static void save_link_var_sym(const char *var, struct symbol *sym, const char *link)
626 {
627 struct smatch_state *old_state, *new_state;
628 struct string_list *links;
629 char *new;
630
631 old_state = get_state(link_id, var, sym);
632 if (old_state)
633 links = clone_str_list(old_state->data);
634 else
635 links = NULL;
636
637 new = alloc_sname(link);
638 insert_string(&links, new);
639
640 new_state = alloc_link_state(links);
641 set_state(link_id, var, sym, new_state);
642 }
643
644 static void match_inc(struct sm_state *sm)
645 {
646 struct string_list *links;
647 struct smatch_state *state, *new;
648 struct compare_data *data;
649 char *tmp;
650 int flip;
651 int op;
652
653 links = sm->state->data;
654
655 FOR_EACH_PTR(links, tmp) {
656 state = get_state(compare_id, tmp, NULL);
657 if (!state)
658 continue;
659 data = state->data;
660 if (!data)
661 continue;
662
663 flip = 0;
664 if (strncmp(sm->name, tmp, strlen(sm->name)) != 0 ||
665 tmp[strlen(sm->name)] != ' ')
666 flip = 1;
667
668 op = state_to_comparison(state);
669
670 switch (flip ? flip_comparison(op) : op) {
671 case SPECIAL_EQUAL:
672 case SPECIAL_GTE:
673 case SPECIAL_UNSIGNED_GTE:
674 case '>':
675 case SPECIAL_UNSIGNED_GT:
676 new = alloc_compare_state(
677 data->left, data->left_var, data->left_vsl,
678 flip ? '<' : '>',
679 data->right, data->right_var, data->right_vsl);
680 set_state(compare_id, tmp, NULL, new);
681 break;
682 case '<':
683 case SPECIAL_UNSIGNED_LT:
684 new = alloc_compare_state(
685 data->left, data->left_var, data->left_vsl,
686 flip ? SPECIAL_GTE : SPECIAL_LTE,
687 data->right, data->right_var, data->right_vsl);
688 set_state(compare_id, tmp, NULL, new);
689 break;
690 default:
691 set_state(compare_id, tmp, NULL, &undefined);
692 }
693 } END_FOR_EACH_PTR(tmp);
694 }
695
696 static void match_dec(struct sm_state *sm)
697 {
698 struct string_list *links;
699 struct smatch_state *state;
700 char *tmp;
701
702 links = sm->state->data;
703
704 FOR_EACH_PTR(links, tmp) {
705 state = get_state(compare_id, tmp, NULL);
706
707 switch (state_to_comparison(state)) {
708 case SPECIAL_EQUAL:
709 case SPECIAL_LTE:
710 case SPECIAL_UNSIGNED_LTE:
711 case '<':
712 case SPECIAL_UNSIGNED_LT: {
713 struct compare_data *data = state->data;
714 struct smatch_state *new;
715
716 new = alloc_compare_state(
717 data->left, data->left_var, data->left_vsl,
718 '<',
719 data->right, data->right_var, data->right_vsl);
720 set_state(compare_id, tmp, NULL, new);
721 break;
722 }
723 default:
724 set_state(compare_id, tmp, NULL, &undefined);
725 }
726 } END_FOR_EACH_PTR(tmp);
727 }
728
729 static void match_inc_dec(struct sm_state *sm, struct expression *mod_expr)
730 {
731 /*
732 * if (foo > bar) then ++foo is also > bar.
733 */
734 if (!mod_expr)
735 return;
736 if (mod_expr->type != EXPR_PREOP && mod_expr->type != EXPR_POSTOP)
737 return;
738
739 if (mod_expr->op == SPECIAL_INCREMENT)
740 match_inc(sm);
741 else if (mod_expr->op == SPECIAL_DECREMENT)
742 match_dec(sm);
743 }
744
745 static int is_self_assign(struct expression *expr)
746 {
747 if (!expr || expr->type != EXPR_ASSIGNMENT || expr->op != '=')
748 return 0;
749 return expr_equiv(expr->left, expr->right);
750 }
751
752 static void match_modify(struct sm_state *sm, struct expression *mod_expr)
753 {
754 struct string_list *links;
755 char *tmp;
756
757 if (mod_expr && is_self_assign(mod_expr))
758 return;
759
760 /* handled by match_inc_dec() */
761 if (mod_expr &&
762 ((mod_expr->type == EXPR_PREOP || mod_expr->type == EXPR_POSTOP) &&
763 (mod_expr->op == SPECIAL_INCREMENT || mod_expr->op == SPECIAL_DECREMENT)))
764 return;
765
766 links = sm->state->data;
767
768 FOR_EACH_PTR(links, tmp) {
769 set_state(compare_id, tmp, NULL, &undefined);
770 } END_FOR_EACH_PTR(tmp);
771 set_state(link_id, sm->name, sm->sym, &undefined);
772 }
773
774 static void match_preop(struct expression *expr)
775 {
776 struct expression *parent;
777 struct range_list *left, *right;
778 int op;
779
780 /*
781 * This is an important special case. Say you have:
782 *
783 * if (++j == limit)
784 *
785 * Assume that we know the range of limit is higher than the start
786 * value for "j". Then the first thing that we process is the ++j. We
787 * have not comparison states set up so it doesn't get caught by the
788 * modification hook. But it does get caught by smatch_extra which sets
789 * j to unknown then we parse the "j == limit" and sets false to != but
790 * really we want false to be <.
791 *
792 * So what we do is we set j < limit here, then the match_modify catches
793 * it and we do a match_inc_dec().
794 *
795 */
796
797 if (expr->type != EXPR_PREOP ||
798 (expr->op != SPECIAL_INCREMENT && expr->op != SPECIAL_DECREMENT))
799 return;
800
801 parent = expr_get_parent_expr(expr);
802 if (!parent)
803 return;
804 if (parent->type != EXPR_COMPARE || parent->op != SPECIAL_EQUAL)
805 return;
806 if (parent->left != expr)
807 return;
808
809 if (!get_implied_rl(expr->unop, &left) ||
810 !get_implied_rl(parent->right, &right))
811 return;
812
813 op = rl_comparison(left, right);
814 if (!op)
815 return;
816
817 add_comparison(expr->unop, op, parent->right);
818 }
819
820 static char *chunk_to_var_sym(struct expression *expr, struct symbol **sym)
821 {
822 expr = strip_expr(expr);
823 if (!expr)
824 return NULL;
825 if (sym)
826 *sym = NULL;
827
828 if (expr->type == EXPR_PREOP &&
829 (expr->op == SPECIAL_INCREMENT ||
830 expr->op == SPECIAL_DECREMENT))
831 expr = strip_expr(expr->unop);
832
833 if (expr->type == EXPR_CALL) {
834 char buf[64];
835
836 snprintf(buf, sizeof(buf), "return %p", expr);
837 return alloc_string(buf);
838 }
839
840 return expr_to_chunk_sym_vsl(expr, sym, NULL);
841 }
842
843 static char *chunk_to_var(struct expression *expr)
844 {
845 return chunk_to_var_sym(expr, NULL);
846 }
847
848 static struct smatch_state *get_state_chunk(int owner, struct expression *expr)
849 {
850 char *name;
851 struct symbol *sym;
852 struct smatch_state *ret;
853
854 name = chunk_to_var_sym(expr, &sym);
855 if (!name)
856 return NULL;
857
858 ret = get_state(owner, name, sym);
859 free_string(name);
860 return ret;
861 }
862
863 static void save_link(struct expression *expr, char *link)
864 {
865 char *var;
866 struct symbol *sym;
867
868 expr = strip_expr(expr);
869 if (expr->type == EXPR_BINOP) {
870 char *chunk;
871
872 chunk = chunk_to_var(expr);
873 if (!chunk)
874 return;
875
876 save_link(expr->left, link);
877 save_link(expr->right, link);
878 save_link_var_sym(chunk, NULL, link);
879 return;
880 }
881
882 var = chunk_to_var_sym(expr, &sym);
883 if (!var)
884 return;
885
886 save_link_var_sym(var, sym, link);
887 free_string(var);
888 }
889
890 static int get_orig_comparison(struct stree *pre_stree, const char *left, const char *right)
891 {
892 struct smatch_state *state;
893 struct compare_data *data;
894 int flip = 0;
895 char state_name[256];
896
897 if (strcmp(left, right) > 0) {
898 const char *tmp = right;
899
900 flip = 1;
901 right = left;
902 left = tmp;
903 }
904
905 snprintf(state_name, sizeof(state_name), "%s vs %s", left, right);
906 state = get_state_stree(pre_stree, compare_id, state_name, NULL);
907 if (!state || !state->data)
908 return 0;
909 data = state->data;
910 if (flip)
911 return flip_comparison(data->comparison);
912 return data->comparison;
913
914 }
915
916 static int have_common_var_sym(struct var_sym_list *left_vsl, struct var_sym_list *right_vsl)
917 {
918 struct var_sym *tmp;
919
920 FOR_EACH_PTR(left_vsl, tmp) {
921 if (in_var_sym_list(right_vsl, tmp->var, tmp->sym))
922 return 1;
923 } END_FOR_EACH_PTR(tmp);
924
925 return 0;
926 }
927
928 /*
929 * The idea here is that we take a comparison "a < b" and then we look at all
930 * the things which "b" is compared against "b < c" and we say that that implies
931 * a relationship "a < c".
932 *
933 * The names here about because the comparisons are organized like this
934 * "a < b < c".
935 *
936 */
937 static void update_tf_links(struct stree *pre_stree,
938 struct expression *left_expr,
939 const char *left_var, struct var_sym_list *left_vsl,
940 int left_comparison, int left_false_comparison,
941 const char *mid_var, struct var_sym_list *mid_vsl,
942 struct string_list *links)
943 {
944 struct smatch_state *state;
945 struct smatch_state *true_state, *false_state;
946 struct compare_data *data;
947 struct expression *right_expr;
948 const char *right_var;
949 struct var_sym_list *right_vsl;
950 int orig_comparison;
951 int right_comparison;
952 int true_comparison;
953 int false_comparison;
954 char *tmp;
955 char state_name[256];
956 struct var_sym *vs;
957
958 FOR_EACH_PTR(links, tmp) {
959 state = get_state_stree(pre_stree, compare_id, tmp, NULL);
960 if (!state || !state->data)
961 continue;
962 data = state->data;
963 right_comparison = data->comparison;
964 right_expr = data->right;
965 right_var = data->right_var;
966 right_vsl = data->right_vsl;
967 if (strcmp(mid_var, right_var) == 0) {
968 right_expr = data->left;
969 right_var = data->left_var;
970 right_vsl = data->left_vsl;
971 right_comparison = flip_comparison(right_comparison);
972 }
973 if (have_common_var_sym(left_vsl, right_vsl))
974 continue;
975
976 orig_comparison = get_orig_comparison(pre_stree, left_var, right_var);
977
978 true_comparison = combine_comparisons(left_comparison, right_comparison);
979 false_comparison = combine_comparisons(left_false_comparison, right_comparison);
980
981 true_comparison = filter_comparison(orig_comparison, true_comparison);
982 false_comparison = filter_comparison(orig_comparison, false_comparison);
983
984 if (strcmp(left_var, right_var) > 0) {
985 struct expression *tmp_expr = left_expr;
986 const char *tmp_var = left_var;
987 struct var_sym_list *tmp_vsl = left_vsl;
988
989 left_expr = right_expr;
990 left_var = right_var;
991 left_vsl = right_vsl;
992 right_expr = tmp_expr;
993 right_var = tmp_var;
994 right_vsl = tmp_vsl;
995 true_comparison = flip_comparison(true_comparison);
996 false_comparison = flip_comparison(false_comparison);
997 }
998
999 if (!true_comparison && !false_comparison)
1000 continue;
1001
1002 if (true_comparison)
1003 true_state = alloc_compare_state(
1004 left_expr, left_var, left_vsl,
1005 true_comparison,
1006 right_expr, right_var, right_vsl);
1007 else
1008 true_state = NULL;
1009 if (false_comparison)
1010 false_state = alloc_compare_state(
1011 left_expr, left_var, left_vsl,
1012 false_comparison,
1013 right_expr, right_var, right_vsl);
1014 else
1015 false_state = NULL;
1016
1017 snprintf(state_name, sizeof(state_name), "%s vs %s", left_var, right_var);
1018 set_true_false_states(compare_id, state_name, NULL, true_state, false_state);
1019 FOR_EACH_PTR(left_vsl, vs) {
1020 save_link_var_sym(vs->var, vs->sym, state_name);
1021 } END_FOR_EACH_PTR(vs);
1022 FOR_EACH_PTR(right_vsl, vs) {
1023 save_link_var_sym(vs->var, vs->sym, state_name);
1024 } END_FOR_EACH_PTR(vs);
1025 if (!vsl_to_sym(left_vsl))
1026 save_link_var_sym(left_var, NULL, state_name);
1027 if (!vsl_to_sym(right_vsl))
1028 save_link_var_sym(right_var, NULL, state_name);
1029 } END_FOR_EACH_PTR(tmp);
1030 }
1031
1032 static void update_tf_data(struct stree *pre_stree,
1033 struct expression *left_expr,
1034 const char *left_name, struct var_sym_list *left_vsl,
1035 struct expression *right_expr,
1036 const char *right_name, struct var_sym_list *right_vsl,
1037 int true_comparison, int false_comparison)
1038 {
1039 struct smatch_state *state;
1040
1041 state = get_state_stree(pre_stree, link_id, right_name, vsl_to_sym(right_vsl));
1042 if (state)
1043 update_tf_links(pre_stree, left_expr, left_name, left_vsl, true_comparison, false_comparison, right_name, right_vsl, state->data);
1044
1045 state = get_state_stree(pre_stree, link_id, left_name, vsl_to_sym(left_vsl));
1046 if (state)
1047 update_tf_links(pre_stree, right_expr, right_name, right_vsl, flip_comparison(true_comparison), flip_comparison(false_comparison), left_name, left_vsl, state->data);
1048 }
1049
1050 static void iter_modify(struct sm_state *sm, struct expression *mod_expr)
1051 {
1052 if (sm->state != &start ||
1053 !mod_expr ||
1054 (mod_expr->type != EXPR_PREOP && mod_expr->type != EXPR_POSTOP) ||
1055 mod_expr->op != SPECIAL_INCREMENT)
1056 set_state(inc_dec_id, sm->name, sm->sym, &undefined);
1057 else
1058 set_state(inc_dec_id, sm->name, sm->sym, &incremented);
1059 }
1060
1061 static void handle_for_loops(struct expression *expr, char *state_name, struct smatch_state *false_state)
1062 {
1063 sval_t sval;
1064 char *iter_name, *cap_name;
1065 struct symbol *iter_sym, *cap_sym;
1066 struct compare_data *data;
1067
1068 if (expr->op != '<' && expr->op != SPECIAL_UNSIGNED_LT)
1069 return;
1070
1071 if (!__cur_stmt || !__prev_stmt)
1072 return;
1073 if (__cur_stmt->type != STMT_ITERATOR)
1074 return;
1075 if (__cur_stmt->iterator_pre_condition != expr)
1076 return;
1077
1078 /* literals are handled in smatch_extra.c */
1079 if (get_value(expr->right, &sval))
1080 return;
1081
1082 /* First time checking the condition */
1083 if (__prev_stmt == __cur_stmt->iterator_pre_statement) {
1084 if (!get_implied_value(expr->left, &sval) ||
1085 sval.value != 0)
1086 return;
1087
1088 iter_name = expr_to_var_sym(expr->left, &iter_sym);
1089 cap_name = expr_to_var_sym(expr->right, &cap_sym);
1090 if (!iter_name || !cap_name || !iter_sym || !cap_sym) {
1091 free_string(iter_name);
1092 free_string(cap_name);
1093 return;
1094 }
1095
1096 set_state(inc_dec_id, iter_name, iter_sym, &start);
1097 store_link(inc_dec_link_id, cap_name, cap_sym, iter_name, iter_sym);
1098
1099 free_string(iter_name);
1100 free_string(cap_name);
1101 return;
1102 }
1103
1104 /* Second time checking the condtion */
1105 if (__prev_stmt != __cur_stmt->iterator_post_statement)
1106 return;
1107
1108 if (get_state_chunk(inc_dec_id, expr->left) != &incremented)
1109 return;
1110
1111 data = false_state->data;
1112 false_state = alloc_compare_state(
1113 data->left, data->left_var, data->left_vsl,
1114 SPECIAL_EQUAL,
1115 data->right, data->right_var, data->right_vsl);
1116
1117 set_true_false_states(compare_id, state_name, NULL, NULL, false_state);
1118 }
1119
1120 static int is_plus_one(struct expression *expr)
1121 {
1122 sval_t sval;
1123
1124 if (expr->type != EXPR_BINOP || expr->op != '+')
1125 return 0;
1126 if (!get_implied_value(expr->right, &sval) || sval.value != 1)
1127 return 0;
1128 return 1;
1129 }
1130
1131 static int is_minus_one(struct expression *expr)
1132 {
1133 sval_t sval;
1134
1135 if (expr->type != EXPR_BINOP || expr->op != '-')
1136 return 0;
1137 if (!get_implied_value(expr->right, &sval) || sval.value != 1)
1138 return 0;
1139 return 1;
1140 }
1141
1142 static void move_plus_to_minus_helper(struct expression **left_p, struct expression **right_p)
1143 {
1144 struct expression *left = *left_p;
1145 struct expression *right = *right_p;
1146
1147 /*
1148 * These two are basically equivalent: "foo + 1 != bar" and
1149 * "foo != bar - 1". There are issues with signedness and integer
1150 * overflows. There are also issues with type as well. But let's
1151 * pretend we can ignore all that stuff for now.
1152 *
1153 */
1154
1155 if (!is_plus_one(left))
1156 return;
1157
1158 *left_p = left->left;
1159 *right_p = binop_expression(right, '-', left->right);
1160 }
1161
1162 static void move_plus_to_minus(struct expression **left_p, struct expression **right_p)
1163 {
1164 if (is_plus_one(*left_p) && is_plus_one(*right_p))
1165 return;
1166
1167 move_plus_to_minus_helper(left_p, right_p);
1168 move_plus_to_minus_helper(right_p, left_p);
1169 }
1170
1171 static void handle_comparison(struct expression *left_expr, int op, struct expression *right_expr, char **_state_name, struct smatch_state **_false_state)
1172 {
1173 char *left = NULL;
1174 char *right = NULL;
1175 struct symbol *left_sym, *right_sym;
1176 struct var_sym_list *left_vsl = NULL;
1177 struct var_sym_list *right_vsl = NULL;
1178 int false_op;
1179 int orig_comparison;
1180 struct smatch_state *true_state, *false_state;
1181 static char state_name[256];
1182 struct stree *pre_stree;
1183 sval_t sval;
1184
1185 left_expr = strip_parens(left_expr);
1186 right_expr = strip_parens(right_expr);
1187
1188 false_op = negate_comparison(op);
1189
1190 move_plus_to_minus(&left_expr, &right_expr);
1191
1192 if (op == SPECIAL_UNSIGNED_LT &&
1193 get_implied_value(left_expr, &sval) &&
1194 sval.value == 0)
1195 false_op = SPECIAL_EQUAL;
1196
1197 if (op == SPECIAL_UNSIGNED_GT &&
1198 get_implied_value(right_expr, &sval) &&
1199 sval.value == 0)
1200 false_op = SPECIAL_EQUAL;
1201
1202 left = chunk_to_var_sym(left_expr, &left_sym);
1203 if (!left)
1204 goto free;
1205 if (left_sym)
1206 add_var_sym(&left_vsl, left, left_sym);
1207 else
1208 left_vsl = expr_to_vsl(left_expr);
1209 right = chunk_to_var_sym(right_expr, &right_sym);
1210 if (!right)
1211 goto free;
1212 if (right_sym)
1213 add_var_sym(&right_vsl, right, right_sym);
1214 else
1215 right_vsl = expr_to_vsl(right_expr);
1216
1217 if (strcmp(left, right) > 0) {
1218 char *tmp_name = left;
1219 struct var_sym_list *tmp_vsl = left_vsl;
1220 struct expression *tmp_expr = left_expr;
1221
1222 left = right;
1223 left_vsl = right_vsl;
1224 left_expr = right_expr;
1225 right = tmp_name;
1226 right_vsl = tmp_vsl;
1227 right_expr = tmp_expr;
1228 op = flip_comparison(op);
1229 false_op = flip_comparison(false_op);
1230 }
1231
1232 orig_comparison = get_comparison(left_expr, right_expr);
1233 op = filter_comparison(orig_comparison, op);
1234 false_op = filter_comparison(orig_comparison, false_op);
1235
1236 snprintf(state_name, sizeof(state_name), "%s vs %s", left, right);
1237 true_state = alloc_compare_state(
1238 left_expr, left, left_vsl,
1239 op,
1240 right_expr, right, right_vsl);
1241 false_state = alloc_compare_state(
1242 left_expr, left, left_vsl,
1243 false_op,
1244 right_expr, right, right_vsl);
1245
1246 pre_stree = clone_stree(__get_cur_stree());
1247 update_tf_data(pre_stree, left_expr, left, left_vsl, right_expr, right, right_vsl, op, false_op);
1248 free_stree(&pre_stree);
1249
1250 set_true_false_states(compare_id, state_name, NULL, true_state, false_state);
1251 __compare_param_limit_hook(left_expr, right_expr, state_name, true_state, false_state);
1252 save_link(left_expr, state_name);
1253 save_link(right_expr, state_name);
1254
1255 if (_false_state)
1256 *_false_state = false_state;
1257 if (_state_name)
1258 *_state_name = state_name;
1259 free:
1260 free_string(left);
1261 free_string(right);
1262 }
1263
1264 void __comparison_match_condition(struct expression *expr)
1265 {
1266 struct expression *left, *right, *new_left, *new_right, *tmp;
1267 struct smatch_state *false_state = NULL;
1268 char *state_name = NULL;
1269 int redo, count;
1270
1271 if (expr->type != EXPR_COMPARE)
1272 return;
1273
1274 handle_comparison(expr->left, expr->op, expr->right, &state_name, &false_state);
1275 if (false_state && state_name)
1276 handle_for_loops(expr, state_name, false_state);
1277
1278 left = strip_parens(expr->left);
1279 right = strip_parens(expr->right);
1280
1281 if (left->type == EXPR_BINOP && left->op == '+') {
1282 new_left = left->left;
1283 new_right = binop_expression(right, '-', left->right);
1284 handle_comparison(new_left, expr->op, new_right, NULL, NULL);
1285
1286 new_left = left->right;
1287 new_right = binop_expression(right, '-', left->left);
1288 handle_comparison(new_left, expr->op, new_right, NULL, NULL);
1289 }
1290
1291
1292 redo = 0;
1293 left = strip_parens(expr->left);
1294 right = strip_parens(expr->right);
1295 if (get_last_expr_from_expression_stmt(expr->left)) {
1296 left = get_last_expr_from_expression_stmt(expr->left);
1297 redo = 1;
1298 }
1299 if (get_last_expr_from_expression_stmt(expr->right)) {
1300 right = get_last_expr_from_expression_stmt(expr->right);
1301 redo = 1;
1302 }
1303
1304 if (!redo)
1305 return;
1306
1307 count = 0;
1308 while ((tmp = get_assigned_expr(left))) {
1309 if (count++ > 3)
1310 break;
1311 left = strip_expr(tmp);
1312 }
1313 count = 0;
1314 while ((tmp = get_assigned_expr(right))) {
1315 if (count++ > 3)
1316 break;
1317 right = strip_expr(tmp);
1318 }
1319
1320 handle_comparison(left, expr->op, right, NULL, NULL);
1321 }
1322
1323 static void add_comparison_var_sym(
1324 struct expression *left_expr,
1325 const char *left_name, struct var_sym_list *left_vsl,
1326 int comparison,
1327 struct expression *right_expr,
1328 const char *right_name, struct var_sym_list *right_vsl)
1329 {
1330 struct smatch_state *state;
1331 struct var_sym *vs;
1332 char state_name[256];
1333
1334 if (strcmp(left_name, right_name) > 0) {
1335 struct expression *tmp_expr = left_expr;
1336 const char *tmp_name = left_name;
1337 struct var_sym_list *tmp_vsl = left_vsl;
1338
1339 left_expr = right_expr;
1340 left_name = right_name;
1341 left_vsl = right_vsl;
1342 right_expr = tmp_expr;
1343 right_name = tmp_name;
1344 right_vsl = tmp_vsl;
1345 comparison = flip_comparison(comparison);
1346 }
1347 snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
1348 state = alloc_compare_state(
1349 left_expr, left_name, left_vsl,
1350 comparison,
1351 right_expr, right_name, right_vsl);
1352
1353 set_state(compare_id, state_name, NULL, state);
1354
1355 FOR_EACH_PTR(left_vsl, vs) {
1356 save_link_var_sym(vs->var, vs->sym, state_name);
1357 } END_FOR_EACH_PTR(vs);
1358 FOR_EACH_PTR(right_vsl, vs) {
1359 save_link_var_sym(vs->var, vs->sym, state_name);
1360 } END_FOR_EACH_PTR(vs);
1361 }
1362
1363 static void add_comparison(struct expression *left, int comparison, struct expression *right)
1364 {
1365 char *left_name = NULL;
1366 char *right_name = NULL;
1367 struct symbol *left_sym, *right_sym;
1368 struct var_sym_list *left_vsl, *right_vsl;
1369 struct smatch_state *state;
1370 char state_name[256];
1371
1372 left_name = chunk_to_var_sym(left, &left_sym);
1373 if (!left_name)
1374 goto free;
1375 left_vsl = expr_to_vsl(left);
1376 right_name = chunk_to_var_sym(right, &right_sym);
1377 if (!right_name)
1378 goto free;
1379 right_vsl = expr_to_vsl(right);
1380
1381 if (strcmp(left_name, right_name) > 0) {
1382 struct expression *tmp_expr = left;
1383 struct symbol *tmp_sym = left_sym;
1384 char *tmp_name = left_name;
1385 struct var_sym_list *tmp_vsl = left_vsl;
1386
1387 left = right;
1388 left_name = right_name;
1389 left_sym = right_sym;
1390 left_vsl = right_vsl;
1391 right = tmp_expr;
1392 right_name = tmp_name;
1393 right_sym = tmp_sym;
1394 right_vsl = tmp_vsl;
1395 comparison = flip_comparison(comparison);
1396 }
1397 snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
1398 state = alloc_compare_state(
1399 left, left_name, left_vsl,
1400 comparison,
1401 right, right_name, right_vsl);
1402
1403 set_state(compare_id, state_name, NULL, state);
1404 save_link(left, state_name);
1405 save_link(right, state_name);
1406
1407 free:
1408 free_string(left_name);
1409 free_string(right_name);
1410 }
1411
1412 static void match_assign_add(struct expression *expr)
1413 {
1414 struct expression *right;
1415 struct expression *r_left, *r_right;
1416 sval_t left_tmp, right_tmp;
1417
1418 right = strip_expr(expr->right);
1419 r_left = strip_expr(right->left);
1420 r_right = strip_expr(right->right);
1421
1422 get_absolute_min(r_left, &left_tmp);
1423 get_absolute_min(r_right, &right_tmp);
1424
1425 if (left_tmp.value > 0)
1426 add_comparison(expr->left, '>', r_right);
1427 else if (left_tmp.value == 0)
1428 add_comparison(expr->left, SPECIAL_GTE, r_right);
1429
1430 if (right_tmp.value > 0)
1431 add_comparison(expr->left, '>', r_left);
1432 else if (right_tmp.value == 0)
1433 add_comparison(expr->left, SPECIAL_GTE, r_left);
1434 }
1435
1436 static void match_assign_sub(struct expression *expr)
1437 {
1438 struct expression *right;
1439 struct expression *r_left, *r_right;
1440 int comparison;
1441 sval_t min;
1442
1443 right = strip_expr(expr->right);
1444 r_left = strip_expr(right->left);
1445 r_right = strip_expr(right->right);
1446
1447 if (get_absolute_min(r_right, &min) && sval_is_negative(min))
1448 return;
1449
1450 comparison = get_comparison(r_left, r_right);
1451
1452 switch (comparison) {
1453 case '>':
1454 case SPECIAL_GTE:
1455 if (implied_not_equal(r_right, 0))
1456 add_comparison(expr->left, '>', r_left);
1457 else
1458 add_comparison(expr->left, SPECIAL_GTE, r_left);
1459 return;
1460 }
1461 }
1462
1463 static void match_assign_divide(struct expression *expr)
1464 {
1465 struct expression *right;
1466 struct expression *r_left, *r_right;
1467 sval_t min;
1468
1469 right = strip_expr(expr->right);
1470 r_left = strip_expr(right->left);
1471 r_right = strip_expr(right->right);
1472 if (!get_implied_min(r_right, &min) || min.value <= 1)
1473 return;
1474
1475 add_comparison(expr->left, '<', r_left);
1476 }
1477
1478 static void match_binop_assign(struct expression *expr)
1479 {
1480 struct expression *right;
1481
1482 right = strip_expr(expr->right);
1483 if (right->op == '+')
1484 match_assign_add(expr);
1485 if (right->op == '-')
1486 match_assign_sub(expr);
1487 if (right->op == '/')
1488 match_assign_divide(expr);
1489 }
1490
1491 static void copy_comparisons(struct expression *left, struct expression *right)
1492 {
1493 struct string_list *links;
1494 struct smatch_state *state;
1495 struct compare_data *data;
1496 struct symbol *left_sym, *right_sym;
1497 char *left_var = NULL;
1498 char *right_var = NULL;
1499 struct var_sym_list *left_vsl;
1500 struct expression *expr;
1501 const char *var;
1502 struct var_sym_list *vsl;
1503 int comparison;
1504 char *tmp;
1505
1506 left_var = chunk_to_var_sym(left, &left_sym);
1507 if (!left_var)
1508 goto done;
1509 left_vsl = expr_to_vsl(left);
1510 right_var = chunk_to_var_sym(right, &right_sym);
1511 if (!right_var)
1512 goto done;
1513
1514 state = get_state(link_id, right_var, right_sym);
1515 if (!state)
1516 return;
1517 links = state->data;
1518
1519 FOR_EACH_PTR(links, tmp) {
1520 state = get_state(compare_id, tmp, NULL);
1521 if (!state || !state->data)
1522 continue;
1523 data = state->data;
1524 comparison = data->comparison;
1525 expr = data->right;
1526 var = data->right_var;
1527 vsl = data->right_vsl;
1528 if (strcmp(var, right_var) == 0) {
1529 expr = data->left;
1530 var = data->left_var;
1531 vsl = data->left_vsl;
1532 comparison = flip_comparison(comparison);
1533 }
1534 /* n = copy_from_user(dest, src, n); leads to n <= n which is nonsense */
1535 if (strcmp(left_var, var) == 0)
1536 continue;
1537 add_comparison_var_sym(left, left_var, left_vsl, comparison, expr, var, vsl);
1538 } END_FOR_EACH_PTR(tmp);
1539
1540 done:
1541 free_string(right_var);
1542 }
1543
1544 static void match_assign(struct expression *expr)
1545 {
1546 struct expression *right;
1547
1548 if (expr->op != '=')
1549 return;
1550 if (__in_fake_assign || outside_of_function())
1551 return;
1552
1553 if (is_struct(expr->left))
1554 return;
1555
1556 if (is_self_assign(expr))
1557 return;
1558
1559 copy_comparisons(expr->left, expr->right);
1560 add_comparison(expr->left, SPECIAL_EQUAL, expr->right);
1561
1562 right = strip_expr(expr->right);
1563 if (right->type == EXPR_BINOP)
1564 match_binop_assign(expr);
1565 }
1566
1567 int get_comparison_strings(const char *one, const char *two)
1568 {
1569 char buf[256];
1570 struct smatch_state *state;
1571 int invert = 0;
1572 int ret = 0;
1573
1574 if (!one || !two)
1575 return 0;
1576
1577 if (strcmp(one, two) == 0)
1578 return SPECIAL_EQUAL;
1579
1580 if (strcmp(one, two) > 0) {
1581 const char *tmp = one;
1582
1583 one = two;
1584 two = tmp;
1585 invert = 1;
1586 }
1587
1588 snprintf(buf, sizeof(buf), "%s vs %s", one, two);
1589 state = get_state(compare_id, buf, NULL);
1590 if (state)
1591 ret = state_to_comparison(state);
1592
1593 if (invert)
1594 ret = flip_comparison(ret);
1595
1596 return ret;
1597 }
1598
1599 int get_comparison(struct expression *a, struct expression *b)
1600 {
1601 char *one = NULL;
1602 char *two = NULL;
1603 int ret = 0;
1604
1605 if (!a || !b)
1606 return 0;
1607
1608 a = strip_parens(a);
1609 b = strip_parens(b);
1610
1611 move_plus_to_minus(&a, &b);
1612
1613 one = chunk_to_var(a);
1614 if (!one)
1615 goto free;
1616 two = chunk_to_var(b);
1617 if (!two)
1618 goto free;
1619
1620 ret = get_comparison_strings(one, two);
1621 if (ret)
1622 goto free;
1623
1624 if (is_plus_one(a) || is_minus_one(a)) {
1625 free_string(one);
1626 one = chunk_to_var(a->left);
1627 ret = get_comparison_strings(one, two);
1628 } else if (is_plus_one(b) || is_minus_one(b)) {
1629 free_string(two);
1630 two = chunk_to_var(b->left);
1631 ret = get_comparison_strings(one, two);
1632 }
1633
1634 if (!ret)
1635 goto free;
1636
1637 if ((is_plus_one(a) || is_minus_one(b)) && ret == '<')
1638 ret = SPECIAL_LTE;
1639 else if ((is_minus_one(a) || is_plus_one(b)) && ret == '>')
1640 ret = SPECIAL_GTE;
1641 else
1642 ret = 0;
1643
1644 free:
1645 free_string(one);
1646 free_string(two);
1647
1648 if (!ret)
1649 return comparison_from_extra(a, b);
1650 return ret;
1651 }
1652
1653 int possible_comparison(struct expression *a, int comparison, struct expression *b)
1654 {
1655 char *one = NULL;
1656 char *two = NULL;
1657 int ret = 0;
1658 char buf[256];
1659 struct sm_state *sm;
1660 int saved;
1661
1662 one = chunk_to_var(a);
1663 if (!one)
1664 goto free;
1665 two = chunk_to_var(b);
1666 if (!two)
1667 goto free;
1668
1669
1670 if (strcmp(one, two) == 0 && comparison == SPECIAL_EQUAL) {
1671 ret = 1;
1672 goto free;
1673 }
1674
1675 if (strcmp(one, two) > 0) {
1676 char *tmp = one;
1677
1678 one = two;
1679 two = tmp;
1680 comparison = flip_comparison(comparison);
1681 }
1682
1683 snprintf(buf, sizeof(buf), "%s vs %s", one, two);
1684 sm = get_sm_state(compare_id, buf, NULL);
1685 if (!sm)
1686 goto free;
1687
1688 FOR_EACH_PTR(sm->possible, sm) {
1689 if (!sm->state->data)
1690 continue;
1691 saved = ((struct compare_data *)sm->state->data)->comparison;
1692 if (saved == comparison)
1693 ret = 1;
1694 if (comparison == SPECIAL_EQUAL &&
1695 (saved == SPECIAL_LTE ||
1696 saved == SPECIAL_GTE ||
1697 saved == SPECIAL_UNSIGNED_LTE ||
1698 saved == SPECIAL_UNSIGNED_GTE))
1699 ret = 1;
1700 if (ret == 1)
1701 goto free;
1702 } END_FOR_EACH_PTR(sm);
1703
1704 return ret;
1705 free:
1706 free_string(one);
1707 free_string(two);
1708 return ret;
1709 }
1710
1711 struct state_list *get_all_comparisons(struct expression *expr)
1712 {
1713 struct smatch_state *state;
1714 struct string_list *links;
1715 struct state_list *ret = NULL;
1716 struct sm_state *sm;
1717 char *tmp;
1718
1719 state = get_state_chunk(link_id, expr);
1720 if (!state)
1721 return NULL;
1722 links = state->data;
1723
1724 FOR_EACH_PTR(links, tmp) {
1725 sm = get_sm_state(compare_id, tmp, NULL);
1726 if (!sm)
1727 continue;
1728 // FIXME have to compare name with vsl
1729 add_ptr_list(&ret, sm);
1730 } END_FOR_EACH_PTR(tmp);
1731
1732 return ret;
1733 }
1734
1735 struct state_list *get_all_possible_equal_comparisons(struct expression *expr)
1736 {
1737 struct smatch_state *state;
1738 struct string_list *links;
1739 struct state_list *ret = NULL;
1740 struct sm_state *sm;
1741 char *tmp;
1742
1743 state = get_state_chunk(link_id, expr);
1744 if (!state)
1745 return NULL;
1746 links = state->data;
1747
1748 FOR_EACH_PTR(links, tmp) {
1749 sm = get_sm_state(compare_id, tmp, NULL);
1750 if (!sm)
1751 continue;
1752 if (!strchr(sm->state->name, '='))
1753 continue;
1754 if (strcmp(sm->state->name, "!=") == 0)
1755 continue;
1756 add_ptr_list(&ret, sm);
1757 } END_FOR_EACH_PTR(tmp);
1758
1759 return ret;
1760 }
1761
1762 struct state_list *get_all_possible_not_equal_comparisons(struct expression *expr)
1763 {
1764 struct smatch_state *state;
1765 struct string_list *links;
1766 struct state_list *ret = NULL;
1767 struct sm_state *sm;
1768 struct sm_state *possible;
1769 char *link;
1770
1771 return NULL;
1772
1773 state = get_state_chunk(link_id, expr);
1774 if (!state)
1775 return NULL;
1776 links = state->data;
1777
1778 FOR_EACH_PTR(links, link) {
1779 sm = get_sm_state(compare_id, link, NULL);
1780 if (!sm)
1781 continue;
1782 FOR_EACH_PTR(sm->possible, possible) {
1783 if (strcmp(possible->state->name, "!=") != 0)
1784 continue;
1785 add_ptr_list(&ret, sm);
1786 break;
1787 } END_FOR_EACH_PTR(link);
1788 } END_FOR_EACH_PTR(link);
1789
1790 return ret;
1791 }
1792
1793 static void update_links_from_call(struct expression *left,
1794 int left_compare,
1795 struct expression *right)
1796 {
1797 struct string_list *links;
1798 struct smatch_state *state;
1799 struct compare_data *data;
1800 struct symbol *left_sym, *right_sym;
1801 char *left_var = NULL;
1802 char *right_var = NULL;
1803 struct var_sym_list *left_vsl;
1804 struct expression *expr;
1805 const char *var;
1806 struct var_sym_list *vsl;
1807 int comparison;
1808 char *tmp;
1809
1810 left_var = chunk_to_var_sym(left, &left_sym);
1811 if (!left_var)
1812 goto done;
1813 left_vsl = expr_to_vsl(left);
1814 right_var = chunk_to_var_sym(right, &right_sym);
1815 if (!right_var)
1816 goto done;
1817
1818 state = get_state(link_id, right_var, right_sym);
1819 if (!state)
1820 return;
1821 links = state->data;
1822
1823 FOR_EACH_PTR(links, tmp) {
1824 state = get_state(compare_id, tmp, NULL);
1825 if (!state || !state->data)
1826 continue;
1827 data = state->data;
1828 comparison = data->comparison;
1829 expr = data->right;
1830 var = data->right_var;
1831 vsl = data->right_vsl;
1832 if (strcmp(var, right_var) == 0) {
1833 expr = data->left;
1834 var = data->left_var;
1835 vsl = data->left_vsl;
1836 comparison = flip_comparison(comparison);
1837 }
1838 comparison = combine_comparisons(left_compare, comparison);
1839 if (!comparison)
1840 continue;
1841 add_comparison_var_sym(left, left_var, left_vsl, comparison, expr, var, vsl);
1842 } END_FOR_EACH_PTR(tmp);
1843
1844 done:
1845 free_string(right_var);
1846 }
1847
1848 void __add_return_comparison(struct expression *call, const char *range)
1849 {
1850 struct expression *arg;
1851 int comparison;
1852 char buf[4];
1853
1854 if (!str_to_comparison_arg(range, call, &comparison, &arg))
1855 return;
1856 snprintf(buf, sizeof(buf), "%s", show_special(comparison));
1857 update_links_from_call(call, comparison, arg);
1858 add_comparison(call, comparison, arg);
1859 }
1860
1861 void __add_comparison_info(struct expression *expr, struct expression *call, const char *range)
1862 {
1863 copy_comparisons(expr, call);
1864 }
1865
1866 static char *get_mask_comparison(struct expression *expr, int ignore)
1867 {
1868 struct expression *tmp, *right;
1869 int count, param;
1870 char buf[256];
1871
1872 /* The return value for "return foo & param;" is <= param */
1873
1874 count = 0;
1875 while ((tmp = get_assigned_expr(expr))) {
1876 expr = strip_expr(tmp);
1877 if (count++ > 4)
1878 break;
1879 }
1880
1881 if (expr->type != EXPR_BINOP || expr->op != '&')
1882 return NULL;
1883
1884 right = strip_expr(expr->right);
1885 param = get_param_num(right);
1886
1887 if (param == ignore)
1888 return NULL;
1889
1890 snprintf(buf, sizeof(buf), "[<=$%d]", param);
1891 return alloc_sname(buf);
1892 }
1893
1894 static char *range_comparison_to_param_helper(struct expression *expr, char starts_with, int ignore)
1895 {
1896 struct symbol *param;
1897 char *var = NULL;
1898 char buf[256];
1899 char *ret_str = NULL;
1900 int compare;
1901 int i;
1902
1903 if (!expr)
1904 return NULL;
1905
1906 var = chunk_to_var(expr);
1907 if (!var)
1908 goto try_mask;
1909
1910 i = -1;
1911 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
1912 i++;
1913 if (i == ignore)
1914 continue;
1915 if (!param->ident)
1916 continue;
1917 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
1918 compare = get_comparison_strings(var, buf);
1919 if (!compare)
1920 continue;
1921 if (show_special(compare)[0] != starts_with)
1922 continue;
1923 snprintf(buf, sizeof(buf), "[%s$%d]", show_special(compare), i);
1924 ret_str = alloc_sname(buf);
1925 break;
1926 } END_FOR_EACH_PTR(param);
1927
1928 free_string(var);
1929 if (!ret_str)
1930 goto try_mask;
1931
1932 return ret_str;
1933
1934 try_mask:
1935 if (starts_with == '<')
1936 ret_str = get_mask_comparison(expr, ignore);
1937 return ret_str;
1938 }
1939
1940 char *name_sym_to_param_comparison(const char *name, struct symbol *sym)
1941 {
1942 struct symbol *param;
1943 char buf[256];
1944 int compare;
1945 int i;
1946
1947 i = -1;
1948 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
1949 i++;
1950 if (!param->ident)
1951 continue;
1952 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
1953 compare = get_comparison_strings(name, buf);
1954 if (!compare)
1955 continue;
1956 snprintf(buf, sizeof(buf), "[%s$%d]", show_special(compare), i);
1957 return alloc_sname(buf);
1958 } END_FOR_EACH_PTR(param);
1959
1960 return NULL;
1961 }
1962
1963 char *expr_equal_to_param(struct expression *expr, int ignore)
1964 {
1965 return range_comparison_to_param_helper(expr, '=', ignore);
1966 }
1967
1968 char *expr_lte_to_param(struct expression *expr, int ignore)
1969 {
1970 return range_comparison_to_param_helper(expr, '<', ignore);
1971 }
1972
1973 char *expr_param_comparison(struct expression *expr, int ignore)
1974 {
1975 struct symbol *param;
1976 char *var = NULL;
1977 char buf[256];
1978 char *ret_str = NULL;
1979 int compare;
1980 int i;
1981
1982 var = chunk_to_var(expr);
1983 if (!var)
1984 goto free;
1985
1986 i = -1;
1987 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
1988 i++;
1989 if (i == ignore)
1990 continue;
1991 if (!param->ident)
1992 continue;
1993 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
1994 compare = get_comparison_strings(var, buf);
1995 if (!compare)
1996 continue;
1997 snprintf(buf, sizeof(buf), "[%s$%d]", show_special(compare), i);
1998 ret_str = alloc_sname(buf);
1999 break;
2000 } END_FOR_EACH_PTR(param);
2001
2002 free:
2003 free_string(var);
2004 return ret_str;
2005 }
2006
2007 char *get_printed_param_name(struct expression *call, const char *param_name, struct symbol *param_sym)
2008 {
2009 struct expression *arg;
2010 char *name;
2011 struct symbol *sym;
2012 static char buf[256];
2013 int len;
2014 int i;
2015
2016 i = -1;
2017 FOR_EACH_PTR(call->args, arg) {
2018 i++;
2019
2020 name = expr_to_var_sym(arg, &sym);
2021 if (!name || !sym)
2022 continue;
2023 if (sym != param_sym)
2024 continue;
2025
2026 len = strlen(name);
2027 if (strncmp(name, param_name, len) != 0)
2028 continue;
2029 if (param_name[len] == '\0') {
2030 snprintf(buf, sizeof(buf), "$%d", i);
2031 return buf;
2032 }
2033 if (param_name[len] != '-')
2034 continue;
2035 snprintf(buf, sizeof(buf), "$%d%s", i, param_name + len);
2036 return buf;
2037 } END_FOR_EACH_PTR(arg);
2038
2039 return NULL;
2040 }
2041
2042 static void match_call_info(struct expression *expr)
2043 {
2044 struct expression *arg;
2045 struct smatch_state *state;
2046 struct sm_state *sm;
2047 struct compare_data *data;
2048 int comparison;
2049 struct string_list *links;
2050 char *arg_name;
2051 const char *right_name;
2052 char *link;
2053 char info_buf[256];
2054 int i;
2055
2056 i = -1;
2057 FOR_EACH_PTR(expr->args, arg) {
2058 i++;
2059
2060 state = get_state_chunk(link_id, arg);
2061 if (!state)
2062 continue;
2063
2064 links = state->data;
2065 FOR_EACH_PTR(links, link) {
2066 struct var_sym_list *right_vsl;
2067 struct var_sym *right_vs;
2068
2069
2070 if (strstr(link, " orig"))
2071 continue;
2072 sm = get_sm_state(compare_id, link, NULL);
2073 if (!sm)
2074 continue;
2075 data = sm->state->data;
2076 if (!data || !data->comparison)
2077 continue;
2078 arg_name = expr_to_var(arg);
2079 if (!arg_name)
2080 continue;
2081
2082 right_vsl = NULL;
2083 if (strcmp(data->left_var, arg_name) == 0) {
2084 comparison = data->comparison;
2085 right_name = data->right_var;
2086 right_vsl = data->right_vsl;
2087 } else if (strcmp(data->right_var, arg_name) == 0) {
2088 comparison = flip_comparison(data->comparison);
2089 right_name = data->left_var;
2090 right_vsl = data->left_vsl;
2091 }
2092 if (!right_vsl || ptr_list_size((struct ptr_list *)right_vsl) != 1)
2093 goto free;
2094
2095 right_vs = first_ptr_list((struct ptr_list *)right_vsl);
2096 if (strcmp(right_vs->var, right_name) != 0)
2097 goto free;
2098 right_name = get_printed_param_name(expr, right_vs->var, right_vs->sym);
2099 if (!right_name)
2100 goto free;
2101 snprintf(info_buf, sizeof(info_buf), "%s %s", show_special(comparison), right_name);
2102 sql_insert_caller_info(expr, PARAM_COMPARE, i, "$", info_buf);
2103
2104 free:
2105 free_string(arg_name);
2106 } END_FOR_EACH_PTR(link);
2107 } END_FOR_EACH_PTR(arg);
2108 }
2109
2110 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *link_sm)
2111 {
2112 struct sm_state *compare_sm;
2113 struct string_list *links;
2114 char *link;
2115 struct compare_data *data;
2116 struct var_sym *left, *right;
2117 static char info_buf[256];
2118 const char *right_name;
2119
2120 if (strstr(printed_name, " orig"))
2121 return;
2122
2123 links = link_sm->state->data;
2124 FOR_EACH_PTR(links, link) {
2125 compare_sm = get_sm_state(compare_id, link, NULL);
2126 if (!compare_sm)
2127 continue;
2128 data = compare_sm->state->data;
2129 if (!data || !data->comparison)
2130 continue;
2131
2132 if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
2133 ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
2134 continue;
2135 left = first_ptr_list((struct ptr_list *)data->left_vsl);
2136 right = first_ptr_list((struct ptr_list *)data->right_vsl);
2137 if (left->sym == right->sym &&
2138 strcmp(left->var, right->var) == 0)
2139 continue;
2140 /*
2141 * Both parameters link to this comparison so only
2142 * record the first one.
2143 */
2144 if (left->sym != link_sm->sym ||
2145 strcmp(left->var, link_sm->name) != 0)
2146 continue;
2147
2148 right_name = get_printed_param_name(call, right->var, right->sym);
2149 if (!right_name)
2150 continue;
2151 snprintf(info_buf, sizeof(info_buf), "%s %s", show_special(data->comparison), right_name);
2152 sql_insert_caller_info(call, PARAM_COMPARE, param, printed_name, info_buf);
2153 } END_FOR_EACH_PTR(link);
2154 }
2155
2156 static void print_return_value_comparison(int return_id, char *return_ranges, struct expression *expr)
2157 {
2158 char *name;
2159 const char *tmp_name;
2160 struct symbol *sym;
2161 int param;
2162 char info_buf[256];
2163
2164 /*
2165 * TODO: This only prints == comparisons. That's probably the most
2166 * useful comparison because == max has lots of implications. But it
2167 * would be good to capture the rest as well.
2168 *
2169 * This information is already in the DB but it's in the parameter math
2170 * bits and it's awkward to use it. This is is the simpler, possibly
2171 * cleaner way, but not necessarily the best, I don't know.
2172 */
2173
2174 if (!expr)
2175 return;
2176 name = expr_to_var_sym(expr, &sym);
2177 if (!name || !sym)
2178 goto free;
2179
2180 param = get_param_num_from_sym(sym);
2181 if (param < 0)
2182 goto free;
2183 if (param_was_set_var_sym(name, sym))
2184 goto free;
2185
2186 tmp_name = get_param_name_var_sym(name, sym);
2187 if (!tmp_name)
2188 goto free;
2189
2190 snprintf(info_buf, sizeof(info_buf), "== $%d%s", param, tmp_name + 1);
2191 sql_insert_return_states(return_id, return_ranges,
2192 PARAM_COMPARE, -1, "$", info_buf);
2193 free:
2194 free_string(name);
2195 }
2196
2197 static void print_return_comparison(int return_id, char *return_ranges, struct expression *expr)
2198 {
2199 struct sm_state *tmp;
2200 struct string_list *links;
2201 char *link;
2202 struct sm_state *sm;
2203 struct compare_data *data;
2204 struct var_sym *left, *right;
2205 int left_param, right_param;
2206 char left_buf[256];
2207 char right_buf[256];
2208 char info_buf[256];
2209 const char *tmp_name;
2210
2211 print_return_value_comparison(return_id, return_ranges, expr);
2212
2213 FOR_EACH_MY_SM(link_id, __get_cur_stree(), tmp) {
2214 if (get_param_num_from_sym(tmp->sym) < 0)
2215 continue;
2216 links = tmp->state->data;
2217 FOR_EACH_PTR(links, link) {
2218 sm = get_sm_state(compare_id, link, NULL);
2219 if (!sm)
2220 continue;
2221 data = sm->state->data;
2222 if (!data || !data->comparison)
2223 continue;
2224 if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
2225 ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
2226 continue;
2227 left = first_ptr_list((struct ptr_list *)data->left_vsl);
2228 right = first_ptr_list((struct ptr_list *)data->right_vsl);
2229 if (left->sym == right->sym &&
2230 strcmp(left->var, right->var) == 0)
2231 continue;
2232 /*
2233 * Both parameters link to this comparison so only
2234 * record the first one.
2235 */
2236 if (left->sym != tmp->sym ||
2237 strcmp(left->var, tmp->name) != 0)
2238 continue;
2239
2240 if (strstr(right->var, " orig"))
2241 continue;
2242
2243 left_param = get_param_num_from_sym(left->sym);
2244 right_param = get_param_num_from_sym(right->sym);
2245 if (left_param < 0 || right_param < 0)
2246 continue;
2247
2248 tmp_name = get_param_name_var_sym(left->var, left->sym);
2249 if (!tmp_name)
2250 continue;
2251 snprintf(left_buf, sizeof(left_buf), "%s", tmp_name);
2252
2253 tmp_name = get_param_name_var_sym(right->var, right->sym);
2254 if (!tmp_name || tmp_name[0] != '$')
2255 continue;
2256 snprintf(right_buf, sizeof(right_buf), "$%d%s", right_param, tmp_name + 1);
2257
2258 /*
2259 * FIXME: this should reject $ type variables (as
2260 * opposed to $->foo type). Those should come from
2261 * smatch_param_compare_limit.c.
2262 */
2263
2264 snprintf(info_buf, sizeof(info_buf), "%s %s", show_special(data->comparison), right_buf);
2265 sql_insert_return_states(return_id, return_ranges,
2266 PARAM_COMPARE, left_param, left_buf, info_buf);
2267 } END_FOR_EACH_PTR(link);
2268
2269 } END_FOR_EACH_SM(tmp);
2270 }
2271
2272 static int parse_comparison(char **value, int *op)
2273 {
2274
2275 *op = **value;
2276
2277 switch (*op) {
2278 case '<':
2279 (*value)++;
2280 if (**value == '=') {
2281 (*value)++;
2282 *op = SPECIAL_LTE;
2283 }
2284 break;
2285 case '=':
2286 (*value)++;
2287 (*value)++;
2288 *op = SPECIAL_EQUAL;
2289 break;
2290 case '!':
2291 (*value)++;
2292 (*value)++;
2293 *op = SPECIAL_NOTEQUAL;
2294 break;
2295 case '>':
2296 (*value)++;
2297 if (**value == '=') {
2298 (*value)++;
2299 *op = SPECIAL_GTE;
2300 }
2301 break;
2302 default:
2303 return 0;
2304 }
2305
2306 if (**value != ' ') {
2307 sm_msg("internal error parsing comparison. %s", *value);
2308 return 0;
2309 }
2310
2311 (*value)++;
2312 return 1;
2313 }
2314
2315 static int split_op_param_key(char *value, int *op, int *param, char **key)
2316 {
2317 static char buf[256];
2318 char *p;
2319
2320 if (!parse_comparison(&value, op))
2321 return 0;
2322
2323 snprintf(buf, sizeof(buf), value);
2324
2325 p = buf;
2326 if (*p++ != '$')
2327 return 0;
2328
2329 *param = atoi(p);
2330 if (*param < 0 || *param > 99)
2331 return 0;
2332 p++;
2333 if (*param > 9)
2334 p++;
2335 p--;
2336 *p = '$';
2337 *key = p;
2338
2339 return 1;
2340 }
2341
2342 static void db_return_comparison(struct expression *expr, int left_param, char *key, char *value)
2343 {
2344 struct expression *left_arg, *right_arg;
2345 char *left_name = NULL;
2346 struct symbol *left_sym;
2347 char *right_name = NULL;
2348 struct symbol *right_sym;
2349 int op;
2350 int right_param;
2351 char *right_key;
2352 struct var_sym_list *left_vsl = NULL, *right_vsl = NULL;
2353
2354 if (left_param == -1) {
2355 if (expr->type != EXPR_ASSIGNMENT)
2356 return;
2357 left_arg = strip_expr(expr->left);
2358
2359 while (expr->type == EXPR_ASSIGNMENT)
2360 expr = strip_expr(expr->right);
2361 if (expr->type != EXPR_CALL)
2362 return;
2363 } else {
2364 while (expr->type == EXPR_ASSIGNMENT)
2365 expr = strip_expr(expr->right);
2366 if (expr->type != EXPR_CALL)
2367 return;
2368
2369 left_arg = get_argument_from_call_expr(expr->args, left_param);
2370 if (!left_arg)
2371 return;
2372 }
2373
2374 if (!split_op_param_key(value, &op, &right_param, &right_key))
2375 return;
2376
2377 right_arg = get_argument_from_call_expr(expr->args, right_param);
2378 if (!right_arg)
2379 return;
2380
2381 left_name = get_variable_from_key(left_arg, key, &left_sym);
2382 if (!left_name || !left_sym)
2383 goto free;
2384
2385 right_name = get_variable_from_key(right_arg, right_key, &right_sym);
2386 if (!right_name || !right_sym)
2387 goto free;
2388
2389 add_var_sym(&left_vsl, left_name, left_sym);
2390 add_var_sym(&right_vsl, right_name, right_sym);
2391
2392 add_comparison_var_sym(NULL, left_name, left_vsl, op, NULL, right_name, right_vsl);
2393
2394 free:
2395 free_string(left_name);
2396 free_string(right_name);
2397 }
2398
2399 int param_compare_limit_is_impossible(struct expression *expr, int left_param, char *left_key, char *value)
2400 {
2401 struct smatch_state *state;
2402 char *left_name = NULL;
2403 char *right_name = NULL;
2404 struct symbol *left_sym, *right_sym;
2405 struct expression *left_arg, *right_arg;
2406 int op, state_op;
2407 int right_param;
2408 char *right_key;
2409 int ret = 0;
2410 char buf[256];
2411
2412 while (expr->type == EXPR_ASSIGNMENT)
2413 expr = strip_expr(expr->right);
2414 if (expr->type != EXPR_CALL)
2415 return 0;
2416
2417 if (!split_op_param_key(value, &op, &right_param, &right_key))
2418 return 0;
2419
2420 left_arg = get_argument_from_call_expr(expr->args, left_param);
2421 if (!left_arg)
2422 return 0;
2423
2424 right_arg = get_argument_from_call_expr(expr->args, right_param);
2425 if (!right_arg)
2426 return 0;
2427
2428 left_name = get_variable_from_key(left_arg, left_key, &left_sym);
2429 right_name = get_variable_from_key(right_arg, right_key, &right_sym);
2430 if (!left_name || !right_name)
2431 goto free;
2432
2433 snprintf(buf, sizeof(buf), "%s vs %s", left_name, right_name);
2434 state = get_state(compare_id, buf, NULL);
2435 if (!state)
2436 goto free;
2437 state_op = state_to_comparison(state);
2438 if (!state_op)
2439 goto free;
2440
2441 if (!filter_comparison(remove_unsigned_from_comparison(state_op), op))
2442 ret = 1;
2443 free:
2444 free_string(left_name);
2445 free_string(right_name);
2446 return ret;
2447 }
2448
2449 int impossibly_high_comparison(struct expression *expr)
2450 {
2451 struct smatch_state *link_state;
2452 struct sm_state *sm;
2453 struct string_list *links;
2454 char *link;
2455 struct compare_data *data;
2456
2457 link_state = get_state_expr(link_id, expr);
2458 if (!link_state) {
2459 if (expr->type == EXPR_BINOP &&
2460 (impossibly_high_comparison(expr->left) ||
2461 impossibly_high_comparison(expr->right)))
2462 return 1;
2463 return 0;
2464 }
2465
2466 links = link_state->data;
2467 FOR_EACH_PTR(links, link) {
2468 sm = get_sm_state(compare_id, link, NULL);
2469 if (!sm)
2470 continue;
2471 data = sm->state->data;
2472 if (!data)
2473 continue;
2474 if (!possibly_true(data->left, data->comparison, data->right))
2475 return 1;
2476 } END_FOR_EACH_PTR(link);
2477
2478 return 0;
2479 }
2480
2481 static void free_data(struct symbol *sym)
2482 {
2483 if (__inline_fn)
2484 return;
2485 clear_compare_data_alloc();
2486 }
2487
2488 void register_comparison(int id)
2489 {
2490 compare_id = id;
2491 add_hook(&save_start_states, AFTER_DEF_HOOK);
2492 add_unmatched_state_hook(compare_id, unmatched_comparison);
2493 add_pre_merge_hook(compare_id, &pre_merge_hook);
2494 add_merge_hook(compare_id, &merge_compare_states);
2495 add_hook(&free_data, AFTER_FUNC_HOOK);
2496 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
2497 add_split_return_callback(&print_return_comparison);
2498
2499 select_return_states_hook(PARAM_COMPARE, &db_return_comparison);
2500 add_hook(&match_preop, OP_HOOK);
2501 }
2502
2503 void register_comparison_late(int id)
2504 {
2505 add_hook(&match_assign, ASSIGNMENT_HOOK);
2506 }
2507
2508 void register_comparison_links(int id)
2509 {
2510 link_id = id;
2511 add_merge_hook(link_id, &merge_links);
2512 add_modification_hook(link_id, &match_modify);
2513 add_modification_hook_late(link_id, match_inc_dec);
2514
2515 add_member_info_callback(link_id, struct_member_callback);
2516 }
2517
2518 void register_comparison_inc_dec(int id)
2519 {
2520 inc_dec_id = id;
2521 add_modification_hook_late(inc_dec_id, &iter_modify);
2522 }
2523
2524 void register_comparison_inc_dec_links(int id)
2525 {
2526 inc_dec_link_id = id;
2527 set_up_link_functions(inc_dec_id, inc_dec_link_id);
2528 }
2529
2530 static void filter_by_sm(struct sm_state *sm, int op,
2531 struct state_list **true_stack,
2532 struct state_list **false_stack)
2533 {
2534 struct compare_data *data;
2535 int istrue = 0;
2536 int isfalse = 0;
2537
2538 if (!sm)
2539 return;
2540 data = sm->state->data;
2541 if (!data) {
2542 if (sm->merged) {
2543 filter_by_sm(sm->left, op, true_stack, false_stack);
2544 filter_by_sm(sm->right, op, true_stack, false_stack);
2545 }
2546 return;
2547 }
2548
2549 if (data->comparison &&
2550 data->comparison == filter_comparison(data->comparison, op))
2551 istrue = 1;
2552
2553 if (data->comparison &&
2554 data->comparison == filter_comparison(data->comparison, negate_comparison(op)))
2555 isfalse = 1;
2556
2557 if (istrue)
2558 add_ptr_list(true_stack, sm);
2559 if (isfalse)
2560 add_ptr_list(false_stack, sm);
2561
2562 if (sm->merged) {
2563 filter_by_sm(sm->left, op, true_stack, false_stack);
2564 filter_by_sm(sm->right, op, true_stack, false_stack);
2565 }
2566 }
2567
2568 struct sm_state *comparison_implication_hook(struct expression *expr,
2569 struct state_list **true_stack,
2570 struct state_list **false_stack)
2571 {
2572 struct sm_state *sm;
2573 char *left, *right;
2574 int op;
2575 static char buf[256];
2576
2577 if (expr->type != EXPR_COMPARE)
2578 return NULL;
2579
2580 op = expr->op;
2581
2582 left = expr_to_var(expr->left);
2583 right = expr_to_var(expr->right);
2584 if (!left || !right) {
2585 free_string(left);
2586 free_string(right);
2587 return NULL;
2588 }
2589
2590 if (strcmp(left, right) > 0) {
2591 char *tmp = left;
2592
2593 left = right;
2594 right = tmp;
2595 op = flip_comparison(op);
2596 }
2597
2598 snprintf(buf, sizeof(buf), "%s vs %s", left, right);
2599 sm = get_sm_state(compare_id, buf, NULL);
2600 if (!sm)
2601 return NULL;
2602 if (!sm->merged)
2603 return NULL;
2604
2605 filter_by_sm(sm, op, true_stack, false_stack);
2606 if (!*true_stack && !*false_stack)
2607 return NULL;
2608
2609 if (option_debug)
2610 sm_msg("implications from comparison: (%s)", show_sm(sm));
2611
2612 return sm;
2613 }
Static analysis for C